This invention relates to video-recorders and players and a system for separating horizontal synchronizing signals during playback of the players. The invention relates particularly to a system in which an image signal is subject to Hadamard conversion or time division conversion into multi-channel signals which are subject to band limitations and which are recorded and played back with a plurality of fixed magnetic heads.
Recording and playback apparatuses using fixed-type multi-channel magnetic heads cause jitter and drift in the playback signals and cause time base fluctuation between channels due to positioning errors of the heads or uneven running of the tape.
Often, to solve this problem, a time base correction is inserted into a horizontal blanking phase portion of a converted or multi-channel signal during recording. The correction signal is separated from the averted signal during playback and the thus separated signal is used as a signal to indicate time base fluctuation and thereby to correct the time base. In this case, to achieve time axis correction signals, horizontal synchronizing signals in the image signals are commonly used as is. Because the synchronizing signal is used as is, it serves as a time base correction signal.
For separating the time base correction signal from a converted multi-channel signal during playback, efforts have been made to detect the difference in level between a converted multi-channel signal and a synchronizing signal. That is, hitherto, when a synchronizing signal and a converted multi-channel signal combined as shown as shown in FIG. 1, and the maximum level L.sub.1 of a converted signal a and the level L.sub.2 of a synchronizing signal b were made sufficiently large, a slice level L.sub.0 could be used as the basis for discriminating between levels and for separating the synchronizing signal b.
However, in such a technique, a signal to noise ratio of the converted signal may be such that the converted signal must be made substantially smaller than the synchronizing signal to avoid the effect of noise.